Management of Malignant Arrhythmia in Apical Hypertrophic Cardiomyopathy: A Case Report

Introduction

Hypertrophic cardiomyopathy (HCM), the most common genetic heart disease, is diverse in presentation and phenotypic expression. The disease is well suited for echocardiography, recently with cardiac magnetic resonance (CMR) [1]. However, it is now apparent that most patients with HCM can achieve normal or near-normal life expectancy without disability and usually do not require major treatment interventions. The disease is characterized by diverse clinical, genetic, and morphologic features, including a risk of sudden death from arrhythmia, diastolic dysfunction, or left ventricular outflow tract obstruction, which is the major determinant of progressive heart failure [2].

Apical hypertrophic cardiomyopathy (ApHCM), also referred to as Yamaguchi syndrome, is a type of hypertrophic cardiomyopathy (HCM) characterized by thickening of the heart muscle at the left ventricle’s apex. Imaging studies for apical hypertrophy show a “spade-like” appearance due to thickening localized to the apex of the heart. ApHCM is more sporadic and sarcomere mutations are detected less frequently; however, there are no specific recommendations to guide diagnosis, family screening, and patient risk stratification [3]. Risk stratification in apical hypertrophic cardiomyopathy should integrate multimodality imaging, arrhythmic monitoring, and clinical risk factors, with particular attention to apical aneurysms and myocardial fibrosis [4]. Our case highlights the importance of early diagnosis and secondary prevention to prevent sudden cardiac death in a patient with phenotypic disease.

Case Report

A 41-year-old man with a history of type 1 diabetes mellitus, alcohol use disorder, an episode of alcoholic pancreatitis, and recurrent falls with seizure-like activity, presented to the Emergency Department (ED) with persistent nausea and vomiting for 2 days following a binge drinking episode. He denied experiencing any chest pain, palpitations, or loss of consciousness associated with falling. His mother noted that he had been experiencing recurrent falls, initially evaluated during a previous hospitalization for seizure-like episodes associated with alcohol consumption.

Upon his arrival at the ED, he was hemodynamically stable and did not have any significant findings during his physical examination. Initial laboratory tests indicated serious electrolyte imbalances, which are presented in detail in Table 1. While being monitored in the ED, he experienced runs of NSVT, prompting a rapid response team activation. An electrocardiogram was performed, which revealed polymorphic premature ventricular contractions (PVCs) along with left ventricular hypertrophy (Sokolow-Lyon criteria) and T wave inversions in the precordial leads, as shown in Figure 1. A cardiologist was consulted, who recommended correction of the electrolyte imbalances and evaluation of 2D echocardiography. The patient was treated with IV fluids, IV magnesium sulfate, and IV potassium chloride and reverted to sinus rhythm. Further discussions with the family revealed that he had been evaluated by a cardiologist 4 years ago and was informed that he has a “thick heart muscle”. However, no medications were prescribed at that time due to a history of substance use disorder, specifically cocaine use.

He was admitted to the telemetry unit and initiated on the Clinical Institute Withdrawal Assessment for Alcohol (CIWA) protocol, along with additional supportive measures and electrolyte replacement. An echocardiogram performed during his admission showed severe apical hypertrophy with complete obliteration of the left ventricular (LV) apex, consistent with apical hypertrophic cardiomyopathy with an estimated ejection fraction greater than 55% without any wall motion abnormality, which is shown in Figure 2.

On the second day of admission, a rapid response was activated due to seizure-like activity. During the rapid response, the patient was noted to be hypotensive and quickly experienced sudden cardiac arrest, leading to a Code Blue activation. Telemetry monitoring revealed polymorphic VT, which quickly progressed to ventricular fibrillation, as shown in Figure 3. After approximately 8 minutes of cardiopulmonary resuscitation (CPR), return of spontaneous circulation (ROSC) was achieved. He was then intubated, sedated, and transferred to the intensive care unit (ICU). Two hours later, another Code Blue was initiated for ventricular fibrillation, and ROSC was regained after 3 cycles of CPR. He was stabilized with amiodarone and lidocaine drip, which was discontinued after 24 hours.

Because of his arrhythmia, an electrophysiologist was consulted, who recommended implantation of an implantable cardioverter-defibrillator (ICD). The ICD was successfully implanted, and after the procedure the patient was transitioned to oral amiodarone at a dosage of 400 mg twice daily. He remained vitally stable and was discharged home after an 8-day hospital stay. The key events of the patient’s clinical course are summarized in Table 2. Upon discharge, he was advised to maintain regular follow-up appointments with his cardiologist and to strictly adhere to his prescribed medication regimen.

Discussion

Apical hypertrophic cardiomyopathy is a relatively rare and sporadic variant of hypertrophic obstructive cardiomyopathy (HOCM), accounting for about 8% of cases. It is defined by the unique pathology of left ventricular hypertrophy (LVH) predominantly in the cardiac apex [3]. The condition was first described in 1976 and is characterized by giant negative precordial T waves (negative voltage of >1 mV) on ECG and a spade-like silhouette of the left ventricle (LV). Late gadolinium enhancement (LGE) in cardiac magnetic resonance shows fibrotic areas, and its extent is associated with a poor prognosis in terms of malignant ventricular arrhythmias and sudden cardiac death (SCD). Diastolic heart failure typically develops due to hypertrophied, stiff ventricles, which predispose to atrial dilation and atrial fibrillation (AF) [5]. The condition is diagnosed by echocardiography (ECHO) or CMR demonstrating a wall thickness >15 mm in the LV apex and a maximal apical to posterior wall thickness ratio >1.5. It is more prevalent in men, with male-to-female ratios ranging from 1.6 to 2.8, and tends to present in individuals in their 40s, as in our patient [5]. The condition is divided into 3 distinct forms – pure, mixed, and relative – depending on the location and extent of the hypertrophied myocardium, with the mixed form tending to be more symptomatic [6,7].

Echocardiographic evidence of LV hypertrophy and its extent is proportional to disease severity, diastolic dysfunction, and mortality risk. The ejection fraction (EF) usually ranges from normal to hyperdynamic [8]. Poor prognostic factors in ApHCM include female sex, age less than 41 years, symptoms listed by the New York Heart Association (NYHA), comorbid conditions including hypertension and diabetes, and evidence of left atrial enlargement [9]. Ventricular arrhythmias, including sustained ventricular tachycardia (VT) and ventricular fibrillation (VF), are mainly due to the disorganized arrangement of myocytes and patchy scars that can lead to the dreaded complication of arrhythmogenic sudden cardiac arrest/death.

Non-vasodilatory beta-blockers are the first-line agents prescribed in most cases but are relatively contraindicated in those with substance abuse disorder, as in our patient [10]. Non-dihydropyridine calcium channel blockers are the second-line medical treatment. In patients with sudden cardiac arrest due to VT, implantable cardioverter-defibrillators (ICDs) are an effective method for secondary prevention.

Pathophysiological phenomena distinct to apical hypertrophic cardiomyopathy (ApHCM) include the formation of apical aneurysms and occasional mid-ventricular obstruction with cavity obliteration, defined as LV cavity obliteration during systole. Mid-ventricular obstruction with cavity obliteration (MVOCO) is typically associated with the mixed variant, and in extreme cases cavity obliteration lasts into diastole, leading to paradoxical diastolic jet flow (PJF) [11]. Apical aneurysms usually occur late in the natural course of the disease and are associated with VT, SCD, embolic phenomena, and worsening heart failure. Predictors of apical aneurysm include a long QT interval on ECG, cavity obliteration, PJF on echocardiography, and late gadolinium enhancement by CMR [12]. Ventricular arrhythmias are frequently refractory, and electrophysiologic studies have identified the arrhythmogenic substrate to be located at the rim of the aneurysm.

Patients with worsening symptoms may benefit from surgical interventions such as apical myomectomy, which involves the removal of the hypertrophied myocardium and has been shown to improve functional status. However, heart transplantation remains the definitive therapy for patients with end-stage symptomatic hypertrophic cardiomyopathy [13,14]. While TTE remains a widely used modality for the initial assessment of ApHCM, it may not detect subclinical myocardial dysfunction, especially when global systolic function is preserved. In this context, speckle-tracking echocardiography (STE) enables the assessment of myocardial deformation, revealing impaired longitudinal strain, particularly in the apical segments of patients with ApHCM. STE is also profoundly helpful in differentiating ApHCM from cardiac amyloidosis, another condition that can present with increased wall thickness and diastolic dysfunction [15]. Global longitudinal strain in cardiac amyloidosis shows reduced strain in the basal and mid-ventricular segments with relative preservation at the apex, creating the characteristic “cherry on top” appearance on the strain map [16].

Conclusions

This case shows the course of disease evaluation of apical hypertrophic cardiomyopathy (ApHCM) and its risks for life-threatening ventricular arrhythmias. Our patient’s clinical course involved recurrent ventricular fibrillation and sudden cardiac arrest, showing the importance of early diagnosis, monitoring, and timely intervention, particularly in patients with coexisting substance use disorders. The presence of arrhythmias necessitates individual management strategies, particularly in patients with substance use disorders. The placement of an implantable cardioverter-defibrillator (ICD) in our patient demonstrates its role in secondary prevention of sudden cardiac death in patients with ApHCM.